textproduct: Quad Cities

KEY MESSAGES

- Isolated to scattered (30-50%) convection is expected to continue across west-central Illinois into the evening. A few storms may be strong to severe.

- More fog is expected late tonight into Thursday morning due to light winds and high moisture levels in the atmosphere.

- Outside of another chance of rain with a front late Thursday night into Friday night, rain chances look very limited into next week.

SHORT TERM /THROUGH FRIDAY/

Issued at 140 PM CDT Wed Aug 19 2026

Convection has initiated south of I-80 ahead of the slowly advancing cool front. The convergence along the front is weak as is the overall forcing. Thus the convection should rapidly dissipate with sunset.

Until the sun sets, mid-level lapse rates are respectable with shear slow increasing from an upper level jet streak and an approaching convectively induced vort max. While the probability is low (<25%) an isolated strong to severe storm cannot be ruled out.

Locally heavy rainfall will also be possible with any storm which may result in ponding of water or at worst a low end localized flash flood.

Late tonight into Thursday morning, patchy if not areas of fog are expected to develop due to the light winds. Locally dense fog is possible around or shortly after sunrise which may drop visibilities under one half mile in spots.

Once the fog burns off around mid-morning Thursday, temperatures near normal with slightly lower humidity levels will be seen.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/

Issued at 140 PM CDT Wed Aug 19 2026

Thursday night through Wednesday Assessment...low (20-30%) confidence on late week rain chances

The model consensus continues to point to late Thursday night into Friday evening for another, albeit low, chance of rain with the passage of another front. Given what has happened with the previous front, I would not be surprised if the 20-40% chances for rain are delayed until the Friday/Friday night time period.

As mentioned yesterday, northwest flow aloft means that any disturbance moving through will be moisture starved. Thus the prospects for any rain outside of the more likely Friday/Friday night time period is very limited.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1236 AM CDT Thu Aug 20 2026

VFR conditions will prevail through much of the TAF period, with light and variable winds. Between 09-15z, we will see the potential for fog development. Best chances will be in our south, where a slow moving boundary remains. Although, northern areas have also cleared out and patchy dense fog cannot be ruled out there either as high pressure approaches, especially in river valleys. Opted to largely message fog potential with TEMPO groups at this time. Otherwise, light/variable winds and a mix of clouds/sun will remain after 15z today.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.